Wraithlords are much bigger than the human-sized Wraithguard, but instead of carrying guns that rip holes in space-time, they're either carrying man-importable heavy weapons on their shoulders (like a big-ass rifle) or huge fucking swords. While a wraithlord fills the same role as a Dreadnought in a Space Marine force, you should be damn careful saying that to its face. Firstly, a Wraithlord is proportioned like a fucking (gangly) actual Eldar, and is built out of million-year-old magical elven space machines. It's agile and maneuverable, and unlike the stubby legs and tiny arms of a Dreadnought, a Wraithlord isn't concerned with the cube-square law. Therefore it can wreck your shit as gracefully at it's scale as a normal Eldar Exarch could at your scale. Proportionally, that's a lot of ass-whooping. Secondly, the dude in the Dreadnought isn't just some space marine sergeant who got put on life support and embalmed. The Exarch inside the Wraithlord is the summation of several dead eldar souls layered onto each other like a gestalt consciousness sandwich, all of which are bloodthirsty as hell and pissed that they aren't getting a fresh soul and hot bod to go killing with. These instrumentality-ass motherfuckers are more dead than usual, and instead of bullshit like "honor" and "duty", they're driven by Doom Marine levels of bloodlust and a carnal need to bust a sick move on the battlefield and get back to 360-no-scopeingnerds inferior races.

The one pictured has has all the heavy weapons it could fit on its shoulders AND the huge fucking sword, but there are a couple of things to note in this regard:

Purely in fluff terms, finding a dead Exarch in the Infinity Circuit takes a Warlock or specialist Farseer, so the very notion of talking the Exarch into a wraithbone shell with no dick is setting a pretty high bar in the first place. But suppose you achieve this:

The Exarch is in the Wraithlord, and now the whole thing comes to life and starts grunting "Diiiiick! Where's my diiiick?", and heads straight over to the nearest shelf of space-hairdresser weapons and sticking too many giant anti-tank weapons on its shoulders, AND a huge fucking sword.

You, the bastard psyker who incarcerated the poor fella in there, is hardly likely to start arguing with it about 40k game load-out limits, now are you?

I think not, no. You'd be checking your runes, and pointing the thing in the direction of the nearest Dreadnought with a certain malicious glee in your psychic heart, wouldn't you.

And I can tell you for nothing that, in game terms, it's worth the time spent dicking around with magnets just to see the look on your opponent's face!

Back in ye olde days, Wraithlords were called Eldar Dreadnoughts. Creative, right? GW was more into making the factions different-flavored copies of each other back then. At this point, GW hadn't even made the rule that Dreadnoughts are forever, and the Eldar piloting the "Eldar Dreadnought" was just a normal dude who could get out. That bubbly head on the old models is a cockpit!

Regardless, the Eldar had the honor of having a few named variants of "Eldar Dreadnought" back then:

War-demon Eldar Assault Dreadnought: It came equipped with two Shuriken Catapults, one on each arm, and assumedly two dreadnought close combat weapons.

Banshee Eldar Support Dreadnought: It mounted a missile launcher on its shoulder, carried a flamer in each arm, and assumedly two dreadnought close combat weapons.

War-cry Eldar Assault Dreadnought: It sacrificed its left arm to carry one of several heavy weapons, including a Plasma Cannon, a D-Cannon, and of all things a "Las-cannon". It's right arm seems to have been a Shuriken Catapult and dreadnought close combat weapon.

In 8th Edition Wraithlords clock in at 103 points, an odd but reasonable number for what you get. T8 W10 and a 3+ save will keep it in the battle for a while, but high AP weaponry and/or sustained fire WILL take it down due to its lack of Invulnerable save. Additionally, when at 50% and 20% Wounds remaining it becomes a lot less effective, dropping its Movement, WS and BS by 1 for each step. This becomes almost a non-issue for Iyanden Wraithlords, however. And while an 8" move, Strength 7 and WS 3+ looks good on paper, having only 4 attacks means that it's not likely to kill a lot of infantry. The Ghostglaive is not very expensive at 10 points and gives it a whopping Strength 9 AP-4 DD6, it's more suited against tanks or a wounded Monstrous Creature than blobs of infantry. And given how easy it is to Fall Back now, it cannot easily tarpit big units of infantry. The Wraithlord is best suited for ranged combat, where it has five options for its heavy guns and can pick two of them in any possible configuration. It is possible to pick two of the same and get some extra firepower, but with the new rules a model can pick different targets for different guns so there's no real punishment in doing so. And do not forget that you don't have to shoot all guns of the same type in the same go: if you can destroy a target with one Bright Lance you can aim your other one elsewhere. Do note that the Wraithlord does NOT have Battle Focus, so it suffers a to-hit modifier if it advances with Shuriken weapons; something that War Walkers do not suffer from. With Heavy class weapons, like Bright Lances or AMLs, the penalties are the same between the two.

Shuriken Cannon: This is one of the two cheapest options at 10 points a pop. The only Assault weapon in the list, they are also the shortest ranged of the bunch. No armor penetration unless you roll a 6+, but it makes up for it with a reasonable S6. Don't expect them to perform miracles, but they might work against small blocks of infantry getting too close for comfort. Synergizes quite well with twin flamers and the ghostglaive for CQC variants.

Scatter Laser: Cost the same and have the same S6 as the Shuriken Catapults, but are Heavy 4 and have 36" range to harass infantry at a longer range. No chance at the -3 AP that the Shuriken Catapult has, but this is not your weapon of choice against high-armor save units anyway. Can be used against larger units of infantry at a longer range.

Starcannon: The Eldar Plasma weapons. Clocking in at 30 points per pair, a Starcannon delivers a man-melting S6 AP-3 DD3 damage blast. Now that many heavy infantry models have multiple wounds, this means that the Starcannon can do what Imperial plasma weapons struggle with. Even then, 4 shots at BS 3+ is not going to clear out entire units in one go and they struggle against 3-wound units.

Bright Lance: Your premier anti-vehicle and anti-monster weapon. 36", S8, AP-4 and D6 damage means that it can really ruin the day of whatever it hits. They are expensive at 20 ponits each, but you can't beat them for vehicle popping power. And if you get lucky you might get to use them on a character and vaporize them, but don't count on it.

Missile Launcher: This comes with two fire modes for the more... flexible variants: D6 S4 AP-1 shots to deal with infantry (note that it fares better than the Imperial counterpart) or a single S8 AP-2 D6 damage missile to put a hole in all but the toughest tanks. Less powerful than the Bright Lance against big targets, it makes up for it with its longer range and by being a decent weapon against light infantry. Taking two will increase your Wraithlord's base cost by 50%, so do be careful.

Then there are the wrist-mounted guns. Shuriken Catapults deliver 4 shots at 12", which won't do a lot of good for you. They are free, however, and are marginally useful for saving points on mid-to-long ranged Wraithlords. The Flamers however are a whole other story. Getting two means 2d6 auto-hitting attacks, which is great even at S4 AP0 D1. And if you get close enough to an enemy vehicle and unleash these you might be surprised: as long as the tanks has Toughness 7 or less you're wounding at 5+ and it gets its full save. While these are pretty bad odds, shaving off just one or even two wounds might mean the world when the Wraithlord charges in for the kill. The downside is that they cost 18 for a pair, which is a notable increase in cost on your already pretty pricy platform.

Because they have the Spirit Host keyword, they have synergy with Spiritseers. If you get one within 6" of an enemy, the Wraithlord can reroll all of its 1s on the To Hit rolls against that unit, which can prove to be a life saver when dealing with high priority targets. Do note that this does not work for Flamers. They are also one of two units (the other being Wraithguard/blades) that can benefit from Wraithseer support, either improving their longevity or making charges/advances easier. Furthermore, if you have a battle-forged army you can pick one of the Craftworld Attributes:

Alaitoc: An innate -1 to-hit modifier adds another frustrating layer of durability on the Wraithlord that can help deal with opposing horde-based armies. As many hordes suffer from relatively poor ballistic skills, this attribute will honestly provide more protection against massed fire than any of the saves you'd have to take otherwise. A Catapult and Scatter Laser Wraithlord is reasonable at 123 points and offers a considerable amount of dakka against infantry heavy armies. That said, CQC variants won't get much out of this perk, and unless you're planning heavily around a Wraith build, there are more cost effective options.

Biel-Tan: For mid-range CQC variants, this can help get the most out of twin Catapult/Cannon loadouts, which runs at a decent 123 points. While the re-rolls are quite handy, if you don't plan on engaging in CQC, there are many, far more cost effective Shuri-platforms than this bugger.

Iyanden: Probably the go-to choice for most loadouts, this trait almost completely removes the damage table worn down Wraithlords would otherwise have to deal with. The Wraithlords remain completely unaffected until they burn down to only 2 wounds remaining after which it will either die shortly thereafter, or can be easily brought back to full strength with a single use of Tears of Isha and/or Bonesinger repair session.

Saim-Hann: As mentioned several times, Wraithlords are monsters in melee combat. This attribute helps get them there much more reliably.

Ulthwé: Similarly to Alaitoc, Ulthwé adds another layer of durability, despite the relative unreliability of it. Being able to potentially shake off even mortal wounds is hard to argue against, though you should definitely not expect consistent results.

But are they worth it? Yes, though only if you make a plan for them. You can't simply throw a Wraithlord in your army and expect it to indiscriminately wreck shop. They can get really expensive really quick, making them ill suited as a strict Heavy Weapons platform compared to the Eldar War Walker. While the walkers are more fragile, they're a lot faster, don't deteriorate under fire, get a 5++ save, are cheaper each and can be taken in a squad of 1-3. This means that with just two Starcannons, they're only 95 points each instead of 133. And as they can be taken in squads, they're much more slot efficient. If you're just wanting to pop off Bright Lance, Star Cannon or Missile shots just take them instead. Now for Iyanden or Saim-Hann armies, Wraithlords can truly shine in mixed or CQC roles. If you're facing hordes, GEQ and MEQ armies and/or intend on getting into CQC, a Wraithlord with twin Shuriken Cannons/Scatter Lasers and Flamers can lay down a respectable amount of dakka, then charge in to firmly stomp any infantry left into paste. Even without its Ghostglaive, those bony fists still punch in at S7 a pop, enough to wound even the tinier Wraithguard on a 3+. If you're taking a Wraithlord, a Bonesinger is highly recommended, as one of them combined with the Tears of Isha stratagem can heal 2D3 wounds a turn, letting the W-Lord shake off all but the heaviest of firepower. A Farseer is also recommended, as they're the only form of direct conventional psyker support you can give the W-Lord (in a sad irony for the Spiritseers).

When dealing with Power Ratings all of that goes out the window. Sure, Wraithlords are 2 Power more expensive than a single War Walker, but they get a tougher frame, two extra small arms and a potent weapon for those measily 2 points. They might not be as fast and lack the save, but they make up for it with all the other perks.